Array / String

• [x] Merge Strings Alternately
• [ ] Greatest Common Divisor of Strings
• [ ] Kids With the Greatest Number of Candies
• [ ] Can Place Flowers
• [ ] Reverse Vowels of a String
• [ ] Reverse Words in a String
• [ ] Product of Array Except Self
• [ ] Increasing Triplet Subsequence
• [ ] String Compression

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Two Pointers

• [ ] Move Zeroes
• [ ] Is Subsequence
• [ ] Container With Most Water
• [ ] Max Number of K-Sum Pairs

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Sliding Window

• [ ] Maximum Average Subarray I
• [ ] Maximum Number of Vowels in a Substring of Given Length
• [ ] Max Consecutive Ones III
• [ ] Longest Subarray of 1's After Deleting One Element

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Prefix Sum

• [ ] Find the Highest Altitude
• [ ] Find Pivot Index

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Hash Map / Set

• [ ] Find the Difference of Two Arrays
• [ ] Unique Number of Occurrences
• [ ] Determine if Two Strings Are Close
• [ ] Equal Row and Column Pairs

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Stack

• [ ] Removing Stars From a String
• [ ] Asteroid Collision
• [ ] Decode String

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Queue

• [ ] Number of Recent Calls
• [ ] Dota2 Senate

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Linked List

• [ ] Delete the Middle Node of a Linked List
• [ ] Odd Even Linked List
• [ ] Reverse Linked List
• [ ] Maximum Twin Sum of a Linked List

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Binary Tree - DFS

• [ ] Maximum Depth of Binary Tree
• [ ] Leaf-Similar Trees
• [ ] Count Good Nodes in Binary Tree
• [ ] Path Sum III
• [ ] Longest ZigZag Path in a Binary Tree
• [ ] Lowest Common Ancestor of a Binary Tree

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Binary Tree - BFS

• [ ] Binary Tree Right Side View
• [ ] Maximum Level Sum of a Binary Tree

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Binary Search Tree

• [ ] Search in a Binary Search Tree
• [ ] Delete Node in a BST

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Graphs - DFS

• [ ] Keys and Rooms
• [ ] Number of Provinces
• [ ] Reorder Routes to Make All Paths Lead to the City Zero
• [ ] Evaluate Division

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Graphs - BFS

• [ ] Nearest Exit from Entrance in Maze
• [ ] Rotting Oranges

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Heap / Priority Queue

• [ ] Kth Largest Element in an Array
• [ ] Smallest Number in Infinite Set
• [ ] Maximum Subsequence Score
• [ ] Total Cost to Hire K Workers

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Binary Search

• [ ] Guess Number Higher or Lower
• [ ] Successful Pairs of Spells and Potions
• [ ] Find Peak Element
• [ ] Koko Eating Bananas

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Backtracking

• [ ] Letter Combinations of a Phone Number
• [ ] Combination Sum III

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DP - 1D

• [ ] N-th Tribonacci Number
• [ ] Min Cost Climbing Stairs
• [ ] House Robber
• [ ] Domino and Tromino Tiling

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DP - Multidimensional

• [ ] Unique Paths
• [ ] Longest Common Subsequence
• [ ] Best Time to Buy and Sell Stock with Transaction Fee
• [ ] Edit Distance

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Bit Manipulation

• [ ] Counting Bits
• [ ] Single Number
• [ ] Minimum Flips to Make a OR b Equal to c

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Trie

• [ ] Implement Trie (Prefix Tree)
• [ ] Search Suggestions System

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Intervals

• [ ] Non-overlapping Intervals
• [ ] Minimum Number of Arrows to Burst Balloons

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Monotonic Stack

• [ ] Daily Temperatures
• [ ] Online Stock Span